When face-to-face communications are not practical, people often rely on one or more technological solutions to meet their communications needs. These solutions typically are designed to simulate one or more aspects of face-to-face communications. Traditional telephony systems enable voice communications between callers. Instant messaging (also referred to as “chat”) communications systems enable users to communicate text messages in real time through instant message computer clients that are interconnected by an instant message server. Some instant messaging systems additionally allow users to be represented in a virtual environment by user-controllable graphic objects (referred to as “avatars”). Interactive virtual reality communication systems enable users in remote locations to communicate over multiple real-time channels and to interact with each other by manipulating their respective avatars in a shared three-dimensional virtual space.
Interest in avatar-based virtual reality communications systems has grown with the increased availability of computing systems that have high-processing-power and high-bandwidth network connections. A primary goal of such a virtual reality system is to create a virtual space in which users can interact and communicate using real-time data streams, such as audio, video and text chat streams. The virtual space typically is defined by a computer graphics specification that describes the visual geometry of the space, the colors and textures that are mapped onto the visual geometry, the collision properties that control how users maneuver within the space, and auditory properties, such as, reverberation and sound absorption properties, of the space.
In a typical virtual reality system, each of the users communicates through an interface that is a source, a sink, or both a source and a sink of one or more of the real-time data streams that are supported by the system. By default, the virtual reality system typically connects each source represented in the virtual space to every sink represented in the virtual space, subject to conditions specified in global switching rules, local user preferences, and the properties of objects within the virtual space. These conditions typically are specified in terms of relative distances between objects. For example, some systems are configured so that real-time data stream connections are not established if the separation distance between avatars exceeds a maximum threshold distance. In addition, some objects have been designed to affect how data streams are rendered. For example, a screen object obstructs views and sounds from a particular direction. Other objects are designed to affect the areas of interaction that are associated with a user's avatar when the user's avatar is within the interaction areas of these objects. For example, a podium adapter object increases the size of the audio interaction space of avatars within the interaction space of a virtual podium, and a table adapter object folds the interaction spaces of all of the avatars seated at a virtual table into a common interaction space that spans the virtual table.